Dose-response of different dietary leucine levels on growth performance and amino acid metabolism in piglets differing for aminoadipate-semialdehyde synthase genotypes

Abstract

Dose-response studies of dietary leucine (Leu) in weaners are needed for a proper diet formulation. Dietary Leu effect was assessed in a 3-weeks dose-response trial with a 2 (genotype) x 5 (diets) factorial arrangement on one-hundred weaned pigs (9 to 20 kg body weight (BW)). Pigs differed for a polymorphism at the aminoadipate-semialdehyde synthase (AASS) gene, involved in lysine (Lys) metabolism. Pigs received experimental diets (d7 to d28) differing for the standardized ileal digestible (SID) Leu:Lys: 70%, 85%, 100%, 115%, 130%. Daily feed intake (ADFI), daily gain (ADG) and feed:gain (F:G) in all pigs and ADG and F:G in two classes of BW were analyzed using regression analysis with curvilinear-plateau (CLP) and linear quadratic function (LQ) models. Amino acid (AA) concentrations in plasma, liver, muscle and urine were determined. AASS genotype did not affect the parameters. Dietary Leu affected performance parameters, with a maximum response for ADG and F:G between 100.5% and 110.7% SID Leu:Lys, higher than the usually recommended one, and between 110.5% and 115.4% and between 94.9% and 110.2% SID Leu:Lys for ADG for light and heavy pigs respectively. AA variations in tissues highlighted Leu role in protein synthesis and its influence on the other branched chain AAs.

Determination of Free Amino Acids in Milk, Colostrum and Plasma of Swine via Liquid Chromatography with Fluorescence and UV Detection

“…The more represented FAAs were Ala, Val, Lys, Gln, Gly and Pro, in agreement with previous studies [6,51,52]. In particular, Ala, Arg and Gly were higher with respect to Bertocchi et al [6] and Yang et al [52], but agreed with Yu et al [51]. In conclusion, the proposed method can be very useful to assess the FAA profile in the considered bio-fluids, which has been demonstrated to be strictly related to food intake with regards to dietary intervention in livestock animals.…”

“…According to Bengtsson [50], the correlation between colostrum and/or milk FAAs and their change in the plasma of piglets receiving them is demonstrated. The more represented FAAs were Ala, Val, Lys, Gln, Gly and Pro, in agreement with previous studies [6,51,52]. In particular, Ala, Arg and Gly were higher with respect to Bertocchi et al [6] and Yang et al [52], but agreed with Yu et al [51].…”

“…In blood, plasma and urine, FAA concentration can be a direct consequence of the intake of protein or of AAs themselves. Bertocchi et al [6] observed that a shortage of dietary leucine (Leu) in a pig's diet was associated with the increase of numerous AAs in its blood. Leu is a key signal for muscle deposition as its deficiency can impair body protein synthesis, provoking a loss of AAs [7].…”

“…Moreover, the FAA profiles of colostrum and milk are of utmost interest because they can be related to the modulation of the piglet's growth [9]. The punctual detection of the FAA profile in these matrices may contribute to the study of metabolomics regulation and dysregulation as well as the study of the biological mechanism in which AAs are involved and, in turn, help nutritionists design specific nutritional interventions [6,10].…”

“…Many analytical methods based on HPLC-DAD, HPLC-FLD [16][17][18]26,27] or LC-MS [1,6] after derivatization have been proposed for the determination of FAAs in plasma. In this matrix, which contains relatively high levels of analytes and low levels of interferents, up to 20 FAAs have been quantified.…”